(R)-(-)-2-Pyrrolidinemethanol: A combined experimental and DFT vibrational analysis of monomers, dimers and hydrogen bonding.

Abstract Experimental IR and solution phase spectra of (R)-(−)-2-Pyrrolidinemethanol showing evidence of hydrogen bonding have been interpreted by computing vibrational modes of monomers and dimers with the molecular species due to intra - and inter -molecular hydrogen bonding, at B3LYP/6-311+G(d,p) level density functional theoretical calculations. Computed vibrational frequencies of Boltzmann population-weighted dimers for stretching and bending of O H and N H modes associated with the inter -molecular N H⋯O and O H⋯O hydrogen bonding are in good agreement with the measured IR absorption, Raman and solution-phase IR values near 3289 cm −1 , 3450 cm −1 and 1400–1300 cm −1 . Further, the H⋯O length is shorter in O H⋯O than in N H⋯O by ∼10% suggesting that O H⋯O is a stronger bond. While the solution-phase IR spectral features suggest strong inter -molecular associations, it is short of demonstrating which type of bonding is dominant factor. We conclude that the measured IR, Raman and solution-phase IR spectral features indicate the presence of both types of hydrogen bonds.